The technician, who had unrestricted access to most if not all of NBD's networks, reportedly downloaded terabytes of classified material onto portable hard drives and then carried the trove – equivalent to hundreds of thousands or even millions of printed pages – out of government buildings in a backpack.

Intelligence agencies, including the CIA and M16, routinely share data on counterterrorism and other issues with the NDB.

Swiss authorities, who arrested the technician last year, believe they seized the hard drives before the suspect could sell any of the information to foreign officials or commercial buyers. But a source told Reuters that investigators weren't positive that the suspect hadn't sold or passed on some of the information.

Either way, the breach is being downplayed as the CIA and M16 declined ot comment while oneU.S. official told Reuters he was unaware of the case.